With development of mobile communications technologies and popularization of intelligent terminals, mobile network services are becoming increasingly rich, which makes a more convenient life for people. A positioning service is widely used in transportation navigation, geographical position searching, position information sharing, and the like. People spend most of their time indoors, and 80% of phone calls and data access services also happen indoors. Therefore, indoor positioning applications gradually become hotspot requirements and have abundant services, for example, position navigation inside an airport or a shopping mall, room searching in a large office building, parking space searching, position searching of a shop or a person in a downtown area, and shopping navigation inside a supermarket. These applications require higher positioning precision, for example, a positioning error less than five meters even within one meter, to achieve good user experience.
Conventional positioning services are mainly classified into two types: Global Positioning System (GPS) positioning and mobile cellular network positioning deployed by an operator. A principle of the GPS positioning is as follows: A user terminal calculates distances from the user to satellites by using a detected arrival sequence and time difference of signals simultaneously sent by multiple positioning satellites, usually more than four satellites, and further obtains longitude, latitude, and an elevation of the user according to point locations of the satellites. The GPS positioning may achieve precision within ten meters outdoors, and meets a requirement of an outdoor positioning service; however, the GPS positioning cannot work normally indoors because signals are obstructed. When positioning is performed by using a mobile cellular network, a position range of the user can be preliminarily determined according to a base station position of a cellular cell in which the user is located, and a smaller coverage radius of the cell leads to higher position precision. Further, a time difference of arrival (UTDOA) may be obtained by measuring a distance and an angle of arrival (AoA) between the user and a base station, or by means of combination measurement of multiple cells, so as to calculate a positioning result of higher precision. At present, an outdoor positioning precision goal that can be achieved by a Universal Mobile Telecommunications System (UMTS) or a Long Term Evolution (LTE) system designed by using a 3rd Generation Partnership Project (3GPP) standard is as follows: 67% of positioning errors are less than 50 m, and 95% of the positioning errors are less than 150 m. It can be learned that, outdoor positioning precision obtained by using the conventional GPS and macro cellular network is relatively low and is far from meeting a requirement of indoor positioning precision.